The present invention relates to a surveying apparatus in which an observation optical system is provided with a zoom function.
A surveying apparatus, for instance, a sighting telescope used in a total station or the like has a high power of approximately 30-power and has a problem that it is difficult to perform sighting on a measuring point with a sighting telescope from the beginning. Therefore, in the past, the sighting is performed on the measuring point first visually or by using a sighting device and then, the sighting is performed on the measuring point with the sighting telescope. However, since the visual sighting, the sighting device and the sighting telescope are largely different in power and even if the sighting is performed on the measuring point visually or by using the sighting device, to catch the measuring point in a field of view of the sighting telescope.
Moreover, by providing the zoom function in the telescope, in a state where the measuring point is observed by the telescope, it is possible to change the power but the zoom mechanism is structurally poor in stability of an optical axis and it is difficult to keep a sighting position and thus, the zoom mechanism has not been used in the surveying apparatus, particularly in the total station.